1. Field of the Invention
The invention relates to a hydraulic cylinder/piston arrangement, with one cylinder, which exhibits at least on one side of a piston, which can be adjusted therein, a working chamber connected outwardly by means of a supply pipe for the hydraulic medium and also exhibits a locking device to secure the piston when the hydraulic medium pressure fails.
Hydraulically operated working cylinders are used currently in a variety of connections to move or displace device and machine parts or the like. The most important advantages of these components are their simplicity and reliability and the circumstance that any increase or decrease in the speed and lift force can be obtained over a wide range.
2. Related Art
Arrangements of the aforementioned kind are known, for example, from the AT-PS 302,107, DE-OS 27 27 506, DE-OS 31 43 040, and also the DE-OS 37 32 561 and are used usually due to safety reasons where the piston or the subassemblies moved by said piston are to be secured or locked during a sudden failure of the pressure of the working medium in order to avoid uncontrolled movements. To this end, for the known arrangements of the aforementioned kind locking elements act mechanically on the piston or a piston rod connected thereto, where these locking elements are also operated by means of the or a pressure medium; apart for this, however, an electrical actuation would also be conceivable and possible.
All of the known arrangements of the aforementioned kind have the drawback of a relatively complicated design of the cylinder/piston arrangement, since separate devices or specific designs of the cylinders, pistons, piston rods etc. must always be provided; in addition, to operate the locking elements specific connections, controllers and the like must be provided, a feature that increases in total the complexity of the arrangements, on the one hand, and their susceptibility to trouble, on the other hand.
Another drawback of the known arrangements is that once the locking device has become effective the piston or the subassembly actuated therewith cannot be moved any further--or at least not simply, so that, for example, a transitory manual operation is rendered difficult or impossible. This is especially unpleasant, when, for example, with a hydraulic failure a car door or a convertible top operated with such an arrangement can no longer be completely opened or closed without performing complicated repair work.